Orthopaedic Emergency Module

Cauda Equina Syndrome

A structured learning module for healthcare professionals

Cauda equina syndrome (CES) is a rare but serious spinal emergency. Early recognition and escalation are critical to prevent permanent neurological and functional impairment. This module provides a clear, structured approach to assessing and managing suspected CES.

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Work sequentially

Follow step-by-step for structured learning.

🧠

Think clinically

Apply content to real on-call decisions.

🎯

Red flag focus

Identify symptoms requiring urgent MRI.

↺

Use as reference

Revisit key sections during clinical work.

✏️

Interactive activities

Complete questions to test your understanding.

Orthopaedic Emergency Module

Learning Objectives

By the end of this module you should be able to:

1. Define

Define cauda equina syndrome clearly and accurately.

2. Explain

Explain the pathophysiology of cauda equina compression and relate it to clinical symptoms.

3. Identify red flags

Elicit and interpret key red flag symptoms, including subtle bladder and saddle sensory changes.

4. Examine

Perform and document a focused neurological examination relevant to suspected CES.

5. Interpret imaging

Interpret lumbar MRI findings in the clinical context.

6. Manage

Formulate a management plan including urgency of imaging, escalation pathways, and documentation standards.

CES Learning Module

Why It Matters

Understanding the urgency of early recognition

Cauda equina syndrome is a time-critical neurological emergency.

Consequences of delayed diagnosis

Drag the minute hand clockwise — every 10 minutes of delay reveals another consequence of untreated cauda equina syndrome.

6 complications · drag clockwise

⏱️

Drag the minute hand to start

Each 10 minutes reveals a new consequence

Orthopaedic Emergency Module

Definition & Key Features

What is Cauda Equina Syndrome?

Cauda equina syndrome (CES) is a clinical syndrome caused by compression of the lumbosacral nerve roots within the spinal canal, below the conus medullaris. The condition affects 1–3 people per 100,000 population in England and there are around 8,000 suspected cases every year.

Anatomy

The spinal cord ends at L1 (conus medullaris) in adults and L3 in children. The filum terminale — a fibrous thread of pia mater — extends from the tip of the conus medullaris down to the coccyx, anchoring and stabilising the spinal cord.

The cauda equina consists of multiple lumbosacral nerve roots travelling below the conus medullaris. Lumbar nerves (L1–L5) exit below their corresponding vertebrae; sacral nerves exit through sacral foramina. Compression at this level produces a combination of motor, sensory, bladder, bowel, and sexual dysfunction.

Explanation video · Exiting & Traversing Nerve Roots

Why they're vulnerable: These roots lie centrally within the spinal canal and are unmyelinated, making them very sensitive to compression.

Clinical relevance: The parasympathetic fibres responsible for bladder contraction arise from S2–S4 nerve roots. Compression of these roots leads to the characteristic bladder dysfunction seen in CES.

Bladder Pathophysiology in CES

As the bladder fills, stretch receptors send sensory signals via the sacral nerve roots to the spinal cord and brain, creating conscious awareness of bladder fullness. When voiding is appropriate, parasympathetic fibres from S2–S4 stimulate detrusor contraction while voluntary relaxation of the external urethral sphincter allows urine to pass.

As cauda equina compression worsens, the nerve roots become increasingly damaged, leading to reduced nerve function and loss of normal bladder sensation.

Bladder innervation — parasympathetic control via S2–S4

Think of it like an orchestra:

Sensory nerves — the audience, signalling the hall is filling
Parasympathetic fibres (S2–S4) — the conductor, cueing detrusor contraction
Sphincter — the stage door, must open at the right moment

In CES, the conductor loses control. The hall fills silently — until it overflows.

"FILL – FEEL – FLOW"

FILL — bladder stretches
FEEL — sensory awareness via sacral roots
FLOW — parasympathetic contraction + sphincter relaxation

CES disrupts in sequence:

Feel → Flow → Failure

Early CES: altered urinary sensation, reduced awareness of bladder filling, change in flow.
Late CES: painless urinary retention with overflow risk.

Orthopaedic Emergency Module

Aetiology

What causes Cauda Equina Syndrome?

The aetiology of CES can be thought of as any pathology that compresses the lumbosacral nerve roots within the spinal canal.

Common causes

Select each hotspot on the spine image to reveal a common cause of CES.

Orthopaedic Emergency Module

History Taking in Suspected CES

Symptoms & History

Key clinical features

Patients may present with one or more of the following symptoms:

Back pain and sciatica

Seen in as many as 97% of patients.

Lower limb weakness or sensory change

Weakness and changes in sensation in the lower extremities.

Bladder dysfunction

Disruption of autonomic fibres may cause retention or incontinence in up to 92% of patients.

Bowel dysfunction

Retention or incontinence may occur in up to 72% of patients.

Saddle anaesthesia

Decreased sensation in the perineum is seen in up to 93% of patients.

Sexual dysfunction

May present as reduced sensation, sexual dysfunction, or impotence in men.

These symptoms in isolation are neither specific nor sensitive for CES. A constellation of symptoms should raise clinical suspicion. The onset of perineal anaesthesia associated with bladder dysfunction is typical of the start of CES and the point at which the clock starts on diagnosis and management. Painless urinary retention often has the greatest predictive value as a stand-alone symptom — but indicates late, often irreversible CES.

Interactive: Sort the red flags by importance

Drag to rank these symptoms from most to least concerning for CES. Then reveal the rationale below.

↕ Drag to reorder

⋮⋮ Painless urinary retention

⋮⋮ Bilateral sciatica

⋮⋮ Saddle anaesthesia

⋮⋮ Loss of bladder fullness sensation

⋮⋮ Unilateral sciatica

How to ask — structured history

Bladder function ▼

Avoid asking: "Any problems passing urine?"

Instead ask specifically:

Have you noticed any change in urinary sensation?
Can you still feel when your bladder is full?
Are you having difficulty starting the stream?
Has your urinary stream become weaker?
Do you need to strain to pass urine?
Have you had any incontinence?
Have you lost the urge to pass urine?

⚠️ Loss of bladder fullness sensation is particularly concerning.

Saddle sensation ▼

Ask directly:

Do you have any numbness around the genitals?
Does it feel different when you wipe after using the toilet?
Do you have any numbness or altered sensation between the legs?

Patients may describe this as:

"Numb when wiping"
"Feels different down there"
"Pins and needles in the groin"

This symptom must always be taken seriously.

Bowel function ▼

Ask about:

New faecal incontinence
Loss of awareness of rectal fullness
Constipation occurring alongside neurological symptoms

⚠️ Loss of rectal sensation is more concerning. Isolated constipation is common and non-specific.

Sexual function ▼

Ask sensitively:

Any new erectile difficulty?
Reduced genital sensation?

Patients may not volunteer this without being asked directly.

Bilateral symptoms ▼

Important red flags include:

Bilateral sciatica
Progressive neurological deficit
Severe radicular back pain

Unilateral sciatica alone is not cauda equina syndrome but can still be concerning if present with other neurological symptoms.

❓ Test yourself

A patient with back pain says "I can feel the urge to go but have difficulty starting." Which symptom domain does this most directly represent?

A

Saddle anaesthesia

B

Early bladder dysfunction (CES-I pattern)

C

Painless urinary retention (CES-R pattern)

D

Bowel dysfunction

✓ Correct. Difficulty initiating micturition with preserved urge is characteristic of early neurogenic bladder dysfunction, consistent with CES-I. The urge is still present — the efferent motor arc (S2–S4) is affected but sensation is partially preserved.

✗ Not quite. CES-R presents with painless urinary retention where the urge is completely lost. This patient still has urge — suggesting earlier, incomplete dysfunction consistent with CES-I.

Orthopaedic Emergency Module

Classification of CES

Why classify? And what does it mean clinically?

The classification of CES describes the stage and severity of neurological compromise. Patients may progress through these stages as compression worsens. Classification guides: recognising early or evolving CES, prioritising MRI urgency, guiding surgical referral, and medico-legal documentation.

Interactive: CES classification

Select each classification to reveal definition and features. Then complete the sorting activity below.

▼ CES Suspected (CES-S)

Definition: Symptoms suggestive of CES but without objective evidence of bladder dysfunction.

Possible features:

Bilateral sciatica
Severe low back pain
Subjective saddle sensory change
No urinary retention
Normal bladder scan

⚠️ Urgent MRI required to exclude evolving CES.

▼ CES Incomplete (CES-I)

Definition: Neurogenic bladder dysfunction without established urinary retention.

Typical features:

Altered urinary sensation
Reduced desire to void
Poor urinary stream / straining
Loss of bladder fullness sensation
Saddle sensory disturbance
Elevated post-void residual volume

High risk of progression. Urgent MRI and spinal surgical review required.

▼ CES Retention (CES-R)

Definition: Established painless urinary retention caused by neurogenic bladder dysfunction.

Typical features:

Loss of urge to void
Painless urinary retention
Post-void residual often >500 mL
Overflow incontinence
Saddle anaesthesia
Bilateral neurological deficit

🚨 Emergency spinal decompression is usually indicated.

▼ CES Complete (CES-C)

Definition: Established complete CES with loss of bladder, bowel and saddle function.

Typical features:

Painless urinary retention
Faecal incontinence
Complete saddle anaesthesia
Bilateral lower limb neurological deficit

Represents advanced neurological compromise requiring urgent spinal surgical assessment.

Match the presentation to the classification

Select a scenario on the left, then select the matching classification on the right.

Clinical scenario

68F: Back pain, bilateral leg pain, unable to feel bladder filling, post-void residual 320 mL, intact saddle sensation

55M: Back pain, bilateral leg weakness, complete saddle anaesthesia, post-void residual 650 mL, faecal incontinence

42F: Severe bilateral sciatica, no bladder symptoms, normal bladder scan

38M: Bilateral leg numbness, difficulty initiating micturition, weak stream, saddle tingling, PVR 180 mL

Classification

CES Suspected (CES-S)

CES Incomplete (CES-I)

CES Retention (CES-R)

CES Complete (CES-C)

❓ Test yourself

A 44-year-old woman presents with back pain, altered sensation when wiping, and difficulty initiating micturition. Bladder scan shows a post-void residual of 240 mL. What is the most accurate CES classification?

A

CES Suspected (CES-S)

B

CES Incomplete (CES-I)

C

CES Retention (CES-R)

D

CES Complete (CES-C)

✓ Correct. This is CES-I. There is objective neurogenic bladder dysfunction (elevated PVR, difficulty voiding) and saddle sensory change, but not complete urinary retention. CES-R would require painless retention with loss of voiding urge. The distinction matters — CES-I still carries a high risk of progression to CES-R.

✗ Review the classification. CES-S lacks objective bladder evidence; CES-R requires established painless retention; CES-C requires complete deficit. This patient has objective dysfunction (PVR 240 mL, altered voiding) without complete retention — consistent with CES-I.

Orthopaedic Emergency Module

Cauda Equina Assessment Tool

eCare Clerking Proforma — ##ces

This proforma is available on eCare and should be used for all patients with suspected CES. Type ##ces in any clerking note. Move between questions using the TAB key. History questions can be answered Y/N. Document power out of 5 and sensation out of 2.

1. History screening questions

Impairment of sensation

Loss of feeling or pins and needles between inner thighs or genitals?
Numbness around back passage or buttocks?
Altered feeling when wiping?
Loss of sensation when passing urine?
Loss of sensation when passing stool?

Impairment of bladder

Increasing difficulty initiating urination?
Leaking urine or new pad use?
Difficulty stopping stream?
Loss of awareness of bladder fullness?

Impairment of bowels

Inability to control bowel movement?
Faecal leakage?

Sexual function

New erectile dysfunction?
Reduced genital sensation during intercourse?

2. Neurological examination

Motor: Grade 0–5 | Sensory: 0 = absent, 1 = impaired, 2 = normal

Lower limb (Left / Right)

L2 — Hip flexion: ___ /5
L3 — Quadriceps: ___ /5
L4 — Ankle dorsiflexion: ___ /5
L5 — Big toe dorsiflexion: ___ /5
S1 — Plantarflexion: ___ /5

MRC Power Scale

Perianal sensation (S3–S5)

Pin prick: ___ /2 Soft touch: ___ /2

Reflexes

0 = absent, + = reduced, ++ = normal, +++ = brisk

Knee: L ___ R ___
Ankle: L ___ R ___
Plantars: L ___ R ___

PR examination

Resting tone: ___
Voluntary tone: ___
Involuntary tone: ___

Bladder scan

Pre-void volume: ___ mL
Post-void residual: ___ mL

Orthopaedic Emergency Module

Examination in Suspected CES

What to assess and how to interpret findings

Examination in suspected CES should assess lower limb neurology, sacral function, and bladder involvement. Findings must be interpreted alongside the history — early CES may have subtle or incomplete signs.

1. Lower limb neurological examination

Assess and document:

Motor power (L2–S1 myotomes)
Reflexes (knee, ankle, plantar, clonus)
Sensory testing (dermatomal distribution)
Straight leg raise, if relevant

Dermatomal reference — use alongside motor, reflex, and sacral findings

Myotome quiz — click each blank to reveal

Click each underlined field to reveal the motor, sensory, or reflex for that spinal level.

Level	Motor	Sensory	Reflex
L2	Tap to reveal	Tap to reveal	Tap to reveal
L3	Tap to reveal	Tap to reveal	Tap to reveal
L4	Tap to reveal	Tap to reveal	Tap to reveal
L5	Tap to reveal	Tap to reveal	Tap to reveal
S1/S2	Tap to reveal	Tap to reveal	Tap to reveal
S2–S5	Tap to reveal	Tap to reveal	Tap to reveal

Red flags: Bilateral weakness · Progressive neurological deficit · Reduced reflexes

Important: Motor power may be normal in early CES.

Demonstration video · Lower Limb Neurological Examination

Note: Examination of proprioception and coordination is not imperative in the context of suspected CES.

2. Perianal sensation (S2–S4)

Test light touch sensation in:

Perianal region
Perineum

Sacral sensory assessment — perianal and perineal sensory change is especially important in suspected sacral nerve root involvement

Ask directly: "Does this feel normal compared to elsewhere?"

3. Anal tone

Perform digital rectal examination (DRE) where clinically indicated. Assess:

Resting tone
Voluntary tone (ask patient to squeeze)
Involuntary tone (ask patient to cough)

Anal tone assessment is subjective and examiner-dependent.
Normal tone does not exclude CES.
Reduced tone is typically a late finding.

4. Bladder assessment

Bladder scan is essential when urinary symptoms are present.

Post-void residual (PVR)

<100 mL — generally reassuring

100–200 mL — borderline

>200 mL — concerning

>500 mL — highly concerning

Key point: Painless high residual volume strongly suggests neurogenic retention.

❓ Test yourself

You perform a DRE in a patient with suspected CES and find normal anal tone. Which of the following is the most appropriate conclusion?

A

CES is excluded — normal anal tone rules out significant compression

B

CES cannot be excluded — reduced tone is a late finding and normal tone does not rule out CES

C

MRI should be deferred as the examination is reassuring

D

The DRE should be repeated by a senior clinician before any imaging

✓ Correct. Reduced anal tone is a late finding in CES and is subjective. A normal DRE does not exclude CES — clinical context and other examination findings (saddle sensation, bladder scan) remain essential. Never use normal anal tone to justify withholding urgent MRI.

✗ This is a common clinical pitfall. Normal anal tone should never be used to exclude CES. Reduced tone is a late sign, and the DRE is subjective and examiner-dependent. Always integrate with the full clinical picture.

Orthopaedic Emergency Module

GIRFT CES Pathway

Standardising assessment and urgent imaging decisions

The GIRFT CES pathway provides a nationally recognised framework to support safe and timely assessment of patients with suspected CES. It has been shown to alleviate pressures on the NHS system without impacting diagnosis.

Designed for clinicians across primary care, emergency departments, acute medical units, and surgical specialties, the pathway creates a consistent approach to:

Early identification of red flag symptoms
Standardised documentation
Appropriate escalation pathways
Timely access to urgent MRI scanning
Reducing diagnostic delay and harm

Using a standard pathway helps reduce variation in practice, supports urgent MRI decisions, and may reduce avoidable harm from delayed diagnosis.

Open pathway in a new tab ↗

Interactive GIRFT pathway (scroll down within the frame)

Orthopaedic Emergency Module

Imaging in Suspected CES

MRI Lumbar / Sacral Spine

MRI is the gold standard investigation for suspected cauda equina syndrome. It should be performed urgently when red flag symptoms are present, in line with GIRFT and national pathway guidance.

Why MRI?

Direct visualisation of cauda equina nerve root compression
Identification of large central disc prolapse
Detection of tumour, infection, or haematoma
Assessment of severity and extent of canal compromise

CT myelogram

Can be considered when MRI is contraindicated (e.g. pacemaker, severe claustrophobia). Sagittal and axial reconstructions can identify space-occupying lesions and may demonstrate partial or complete blockage of contrast.

Below are example imaging findings for different aetiological causes of cauda equina syndrome.

Massive central disc prolapse — key features ▼

Large posterior disc extrusion compressing cauda equina roots
Loss of visible CSF around nerve roots
Often midline at L4/5 or L5/S1

Clinical relevance: Urgent referral to spinal surgeons.

Sagittal T2 — Large L5/S1 disc protrusion

Axial T2 — Central canal compromise

Epidural abscess — key features ▼

Epidural collection causing compression
Rim enhancement with contrast
Associated discitis or osteomyelitis

Clinical relevance: Managed with IV antibiotics. Spinal review required to assess need for surgery.

Sagittal T2 — Epidural abscess

Schematic diagram of spinal epidural abscess

Metastatic cord compression — key features ▼

Vertebral body collapse or mass lesion
Epidural soft tissue extension
Compression of neural elements

Clinical relevance: Usually managed under the medical team with urgent oncology input. Spinal review may be required if surgical fixation is indicated.

Sagittal T2 — Metastatic deposit within the T12 vertebral body

Axial T2 — Extension into the epidural space with displacement of the spinal cord

❓ Test yourself

A patient with suspected CES has a pacemaker. What is the most appropriate imaging strategy?

A

CT abdomen and pelvis

B

Ultrasound of the lumbar spine

C

CT myelogram as MRI alternative

D

Plain radiograph of lumbar spine

✓ Correct. CT myelogram is the most appropriate MRI alternative when MRI is contraindicated. It can demonstrate space-occupying lesions, disc extrusions, and neural compression via contrast distribution. Always verify the pacemaker type — some modern devices are MRI-conditional and can be scanned with appropriate precautions.

✗ CT abdomen/pelvis, ultrasound, and plain films cannot adequately assess the cauda equina. When MRI is contraindicated, CT myelogram is the most appropriate alternative for suspected CES.

Orthopaedic Emergency Module

WSH MRI Pathway for Suspected CES

Local operational guidance

MRI availability

Available daily from 08:30–20:00
Patient must be in the scanner by 19:30 for the final slot

Urgency

GIRFT guidance recommends MRI within 4 hours of suspected CES

Out of hours pathway

If presenting after 20:00 with red flag symptoms, discuss with the Ipswich spinal team regarding possible overnight transfer
Ensure this discussion is clearly documented in the clinical notes

Dedicated 08:45 CES slot

This slot is available for overnight admissions deemed suitable for scanning the following morning.

Requirements:

##ces proforma must be completed
Patient must meet MRI criteria
Scan must be requested on eCare
MRI safety questionnaire must be completed
Does not need to be vetted by a radiologist if all the above have been done

Vetting during daytime hours

Scans requested during standard daytime hours must be vetted by the Duty Radiologist (09:00–17:00) or the Out-of-Hours Radiologist (17:00–20:00).

Contacting MRI

Ext: 2891 / 3448
Available from 08:15

Before requesting MRI

MRI safety questionnaire completed
No contraindications identified
Adequate analgesia provided
Patient able to lie flat and remain still

Include in the MRI request

Time of onset of symptoms
Nature of neurological deficits and side
Incontinence versus retention
History of trauma or malignancy
Previous imaging
Previous spinal surgery or implants, including details
Bladder scan result, if available

WSH MRI pathway reference

Orthopaedic Emergency Module

Referring to the Spinal Unit

Ipswich Hospital — CES Referral Process

If spinal unit referral is indicated, this must be completed via referapatient.org.

Referral process

Step 1 — Transfer imaging

Request urgent transfer of relevant images to Ipswich Hospital
Between 09:00–17:00 → contact the PACS team via switchboard
After 17:00 → contact the MRI on-call radiographer via Alertive

Step 2 — Submit online referral

Select New Referral
Select Ipswich Hospital in the first dropdown
Select Spinal Surgery in the second dropdown
Complete with patient details, history, examination findings, and your contact details

Example of the referral platform used for spinal unit referral

Follow-up phone call

All referrals must be followed by a phone call to the spinal fellow at Ipswich Hospital.

Usually completed by the registrar
SHO may call if registrar unavailable
Purpose: avoid delay in management

Documentation requirement

After submission, copy the generated referral link.

Paste the link into the patient notes
Preferably as a separate document
Ensures visibility and team access

Orthopaedic Emergency Module

Management of Suspected CES

Acute stabilisation and definitive treatment

Management should focus on urgent supportive care, rapid investigation, and early spinal referral once compression is suspected or confirmed.

1. Acute management

Request blood tests: FBC, U&Es, CRP (and clotting if indicated)
Catheterise if there is significant urinary retention
Ensure adequate analgesia is prescribed
Keep the patient nil by mouth until imaging and management plan are confirmed

Supportive measures should not delay urgent MRI or spinal referral.

2. Definitive management

Urgent decompressive surgery is the definitive treatment when cauda equina compression is confirmed.

Common procedures

Lumbar discectomy
Laminectomy

Primary goals

Relieve pressure on the cauda equina nerve roots
Prevent further neurological deterioration

3. Transfer to spinal unit

Patients requiring surgical management will need transfer to Ipswich Hospital. Transfer arrangements should follow the instructions provided by the spinal surgeons after referral discussion.

Orthopaedic Emergency Module

Large Disc Herniations Without CES

Pathophysiology and management

1. Pathophysiology

In single nerve root compression, a lumbar disc prolapse compresses one exiting nerve root. Symptoms typically follow a dermatomal pattern and bladder function is preserved.

Common patterns:
L4/5 disc → L5 radiculopathy | L5/S1 disc → S1 radiculopathy

2. Initial management (no CES features)

Adequate analgesia
Neuropathic agents for radicular pain where appropriate (e.g. gabapentin)
Physiotherapy — patients may self-refer to the Back & Neck Service in Suffolk
Activity modification — most disc herniations improve within 6–12 weeks

Safety netting advice

Even if CES is ruled out, patients must be advised to seek urgent review if:

Bladder symptoms develop
Saddle sensory change occurs
Bilateral symptoms appear

The following QR codes can be shared with patients:

Safety Netting Leaflet

Back & Neck Service

3. Indications for surgical referral (non-CES)

Referral may be considered if:

Persistent severe radicular pain despite conservative treatment
Concerning neurological symptoms
Progressive motor weakness
Significant functional limitation
Failure of non-operative management

This is typically urgent elective surgery rather than emergency surgery.

Management documentation checklist

For patients admitted with large disc herniation without CES, ensure the following are clearly documented:

Ipswich spinal plan documented (if discussed)
Analgesia prescribed
Weight bearing status / activity restrictions documented
VTE prophylaxis prescribed if patient does not require urgent transfer
Escalation plan for new/change in neurological symptoms

When to escalate urgently

Even if CES has been ruled out previously, it can develop at any point afterwards. Review urgently if:

Bladder symptoms develop
Saddle sensation changes occur
Bilateral neurological symptoms appear
Rapid neurological deterioration occurs

"The difference between CES-I and CES-R may be hours — and those hours matter."

Clinical Scenarios

Applying Your Knowledge

Work through these two cases before completing the knowledge check

Scenario 1

Weight Lifting Gone Wrong

⏱️ 18:45

You are the orthopaedic SHO on call. A 38-year-old man presents to the Emergency Department with severe lower back pain that started 5 days ago after performing a deadlift in the gym.

The pain has progressively worsened and now radiates down both legs. He describes it as sharp and shooting, worse on movement, and not relieved by simple analgesia.

Over the past 24 hours, he has noticed difficulty passing urine. He feels the urge to go but struggles to start, and when he does, the urinary stream is weak.

He also reports a strange numbness around the inner thighs and perineal area. He is anxious, uncomfortable, and unable to sit still because of the pain.

"I can feel the urge to go, but it's really difficult to start passing urine."

Q1: Which feature in this history is the most important single indicator of neurological bladder dysfunction?

A

Bilateral leg pain radiating from the back

B

Severe back pain not relieved by analgesia

C

Preserved urge but difficulty initiating micturition with weak stream

D

Pain onset after heavy lifting

✓ Correct. The combination of preserved urge with a weak, difficult-to-initiate stream represents early neurogenic bladder dysfunction. This is distinct from CES-R (where urge is lost). Together with perineal numbness, this constellation strongly suggests CES-I.

✗ While bilateral leg pain and onset after lifting are important, neither directly evidences neurological bladder dysfunction. The voiding difficulty with preserved urge is the most specific indicator of early CES-pattern bladder involvement.

Q2: What is the most appropriate immediate next step in management?

A

Prescribe strong analgesia and review in 24 hours

B

Refer to physiotherapy for urgent assessment

C

Complete ##ces proforma, perform bladder scan, and request urgent MRI

D

Request plain lumbar spine X-ray and refer to spinal clinic

✓ Correct. This presentation is consistent with CES-I. The immediate priority is: complete the ##ces proforma, perform bladder scan to quantify residual, and request urgent MRI (within 4 hours per GIRFT guidance). Simultaneous supportive care should not delay imaging.

✗ Delay in investigation is dangerous in suspected CES. Plain X-rays cannot assess neural compression. Physiotherapy referral and deferred review are wholly inappropriate here. Urgent MRI is the gold standard next step.

Q3: The bladder scan shows a post-void residual of 280 mL. How does this inform the CES classification?

A

This is reassuring — PVR under 500 mL suggests the bladder is functioning adequately

B

This confirms objective neurogenic bladder dysfunction, supporting CES-I classification

C

A PVR of 280 mL alone is sufficient to classify this as CES-R

D

PVR is not useful in CES classification

✓ Correct. A PVR of 280 mL is concerning (>200 mL threshold) and combined with the history of voiding difficulty and preserved urge, this objectively confirms neurogenic bladder dysfunction — consistent with CES-I. CES-R requires complete painless retention, which is not the case here.

✗ A PVR of 280 mL is concerning — above the 200 mL threshold and clearly abnormal in context. It confirms objective bladder dysfunction (CES-I), not CES-R (which requires complete painless retention). PVR is a key component of CES classification.

Scenario 2

Pain in the Back

⏱️ 22:40

You are the orthopaedic SHO covering ED. A 43-year-old man has been referred with:

3-day history of worsening lower back pain
Bilateral paraesthesia in his legs
Difficulty walking due to pain

"It feels numb when I wipe."

He denies frank urinary retention.

Observations are normal.

He is otherwise fit and well.

Q1: "It feels numb when I wipe." — How should this symptom be classified and what action does it mandate?

A

Non-specific symptom — reassure and discharge with analgesia

B

Saddle anaesthesia — red flag symptom mandating urgent assessment and MRI

C

Consistent with haemorrhoids — refer to general surgery

D

A late finding of established CES — proceed directly to spinal unit transfer

✓ Correct. "Numb when wiping" is a classical patient description of saddle anaesthesia — one of the most important red flag symptoms of CES. Even in the absence of frank urinary retention, this symptom mandates urgent assessment, ##ces proforma completion, and urgent MRI.

✗ "Numb when wiping" must always be taken seriously — it is a classic patient description of saddle anaesthesia, a key red flag for CES. Never dismiss or attribute this to benign causes without urgent neurological assessment.

Q2: The patient denies urinary retention. Does this reliably exclude CES?

A

Yes — absence of urinary retention means CES can be excluded

B

Yes — the patient is otherwise well and observations are normal

C

No — CES-I and CES-S can present without frank retention; the constellation of features matters

D

Uncertain — arrange an outpatient MRI within 2 weeks

✓ Correct. CES exists on a spectrum. CES-S and CES-I may present without frank retention. The absence of retention does not exclude CES — particularly when there is saddle sensory change and bilateral paraesthesia. Urinary retention is a late and sometimes irreversible sign.

✗ Absence of frank urinary retention does not exclude CES. Painless retention is a late sign. This patient has saddle sensory change and bilateral leg paraesthesia — sufficient to mandate urgent MRI regardless of bladder status.

Q3: It is 22:40 and MRI is unavailable until 08:30. What is the most appropriate management?

A

Discharge with urgent outpatient MRI referral for the following week

B

Admit, prescribe analgesia, and arrange MRI in 08:45 CES slot tomorrow morning

C

Discuss with Ipswich spinal team regarding out-of-hours transfer for imaging and document clearly

D

Await spontaneous symptom resolution overnight before deciding on further management

✓ Correct. When presenting after 20:00 with red flag symptoms, the WSH pathway directs clinicians to discuss with the Ipswich spinal team regarding possible overnight transfer for imaging. The 08:45 slot may be appropriate if the team agree the presentation is stable enough to wait — but this must be a documented clinical decision, not a default.

✗ Review the WSH out-of-hours pathway. Discharge and outpatient referral are inappropriate for suspected CES with red flags. Admitting for the morning MRI slot alone may be reasonable if the Ipswich team agree — but this must follow discussion and be clearly documented.

Module Assessment

Knowledge Check

10 questions covering the full module — attempt each before revealing the answer

Score

0

Progress — 0/10 answered

1. At what vertebral level does the spinal cord (conus medullaris) typically end in adults?

A

T12

B

L1

C

L3

D

L5

✓ Correct. The conus medullaris ends at approximately L1 in adults (L3 in children as the cord migrates proximally during growth).

✗ The conus medullaris ends at approximately L1 in adults. T12 is slightly high; L3 is the level in children; L5 is far below the cord terminus.

2. Which nerve root levels provide the parasympathetic innervation responsible for detrusor contraction?

A

L1–L3

B

L4–L5

C

S2–S4

D

S5–Co

✓ Correct. The parasympathetic innervation of the detrusor muscle arises from S2–S4. Compression of these roots causes the characteristic bladder dysfunction in CES.

✗ The correct answer is S2–S4. These roots carry the parasympathetic fibres that stimulate detrusor contraction — their compression is central to the bladder dysfunction seen in CES.

3. Which single feature carries the greatest predictive value for CES when considered in isolation?

A

Bilateral sciatica

B

Severe back pain

C

Painless urinary retention

D

Saddle tingling

✓ Correct. Painless urinary retention has the greatest predictive value as a stand-alone symptom — but unfortunately indicates late, often irreversible CES.

✗ Painless urinary retention carries the greatest single-symptom predictive value — but this is a late sign indicating advanced, often irreversible CES-R.

4. The most common cause of CES is:

A

Spinal infection (epidural abscess)

B

Large central lumbar disc prolapse

C

Metastatic spinal cord compression

D

Spinal stenosis

✓ Correct. Large central lumbar disc prolapse — typically at L4/5 or L5/S1 — is the most common cause of CES.

✗ Large central lumbar disc prolapse (typically at L4/5 or L5/S1) is the most common cause of CES. While other causes exist, disc prolapse accounts for the majority of cases.

5. A patient with suspected CES is asked about bladder symptoms and says "Not really." What is the problem with this approach?

A

The question should have been asked by a senior clinician

B

The question is too vague — specific closed questions about sensation, stream, and retention are required

C

Bladder symptoms are not relevant unless the patient volunteers them

D

There is no problem — the patient has denied symptoms

✓ Correct. "Any problems passing urine?" is too open-ended and frequently elicits falsely reassuring responses. Specific questions about urinary sensation, desire to void, stream strength, and straining are required. Patients with CES-I may not recognise their symptoms as "problems."

✗ The question is too vague. Patients with early neurogenic bladder dysfunction may not identify their symptoms as "problems." Structured, specific questions — about sensation, stream, straining, and urge — are required to elicit CES-related bladder symptoms reliably.

6. What is the recommended time frame for urgent MRI in suspected CES, according to GIRFT guidance?

A

Within 1 hour

B

Within 4 hours

C

Within 12 hours

D

Within 24 hours

✓ Correct. GIRFT guidance recommends MRI within 4 hours of suspected CES. At WSH, MRI is available from 08:30–20:00 (scanner by 19:30 for the last slot).

✗ GIRFT recommends urgent MRI within 4 hours. A 1-hour target would exceed most departments' current capacity; 12 and 24 hours are too long and risk progression from CES-I to irreversible CES-R.

7. Which myotome is responsible for big toe dorsiflexion (extensor hallucis longus)?

A

L3

B

L4

C

L5

D

S1

✓ Correct. L5 innervates toe extension (EHL — extensor hallucis longus). L4 controls ankle dorsiflexion; S1 controls plantar flexion.

✗ L5 innervates extensor hallucis longus (big toe dorsiflexion). L4 = ankle dorsiflexion; S1 = plantar flexion. The L5 dermatome covers the lateral calf and dorsum of the foot.

8. A CES patient is being admitted overnight for the 08:45 MRI slot. Which of the following must be documented to book this slot without radiologist vetting?

A

Senior review and written consent from patient

B

##ces proforma completed, MRI criteria met, eCare request, MRI safety questionnaire

C

Radiologist verbal approval at time of referral

D

Bladder scan result below 200 mL

✓ Correct. The 08:45 CES slot does not require radiologist vetting if: ##ces proforma is completed, patient meets MRI criteria, scan is requested on eCare, and MRI safety questionnaire is complete. All four conditions must be met.

✗ The 08:45 slot bypasses radiologist vetting only when four criteria are met: ##ces proforma completed, MRI criteria satisfied, eCare request made, and MRI safety questionnaire completed. Radiologist verbal approval would be required if these steps haven't been completed.

9. After submitting a referapatient.org referral to Ipswich, what additional step must be completed?

A

Print a copy of the referral and file in the patient's notes

B

Wait for the spinal unit to contact you

C

Follow up with a phone call to the Ipswich spinal fellow AND paste the referral link in the patient's notes

D

Inform the ward nurse only — the consultant will follow up

✓ Correct. Two additional steps are required after online submission: (1) a follow-up phone call to the spinal fellow at Ipswich, and (2) the generated referral link must be pasted into the patient's notes. Both are essential to avoid delays.

✗ Submitting the online referral is not sufficient on its own. A follow-up phone call to the Ipswich spinal fellow is mandatory, and the referral link must be documented in the patient's notes. This two-step process is designed to prevent communication breakdown and delay.

10. A patient with a large disc herniation is discharged after CES has been excluded. Which of the following is the most important safety net instruction?

A

Return to ED if back pain worsens

B

Attend GP within one week for follow-up

C

Return immediately if bladder symptoms develop, saddle sensation changes, or bilateral symptoms appear

D

Avoid exercise for 12 weeks

✓ Correct. CES can develop at any time after initial exclusion. Patients must be advised to return immediately if bladder symptoms develop, saddle sensation changes, or bilateral neurological symptoms appear. These are the specific CES red flags that cannot wait for GP review.

✗ The critical safety-net advice is to return immediately for any bladder symptoms, saddle sensory change, or bilateral neurological symptoms. These are the specific CES warning signs. General advice about worsening pain or routine follow-up is not specific enough.

🏅

Module Complete

Cauda Equina Syndrome — Orthopaedic Emergency Module

—

Knowledge check score

18

Sections completed

What you have covered

Definition and anatomy of cauda equina syndrome
Pathophysiology of bladder dysfunction in CES
Aetiology and common causes of compression
Structured history taking and red flag identification
CES classification (CES-S, CES-I, CES-R, CES-C)
Focused neurological examination including myotomes, perianal sensation, anal tone, and bladder scan
GIRFT CES pathway and local MRI pathway at WSH
Imaging interpretation — disc prolapse, epidural abscess, metastatic compression
Referral process to Ipswich spinal unit
Acute and definitive management of CES
Management of large disc herniations without CES and safety netting

Key clinical reminders

Never use normal anal tone to exclude CES
Painless retention is a late and often irreversible sign — do not wait for it
Ask specific bladder questions — not "any problems passing urine?"
Saddle sensory change combined with bladder symptoms = start the clock
Supportive care must not delay urgent MRI
Document the referral link in the patient's notes

"The difference between CES-I and CES-R may be hours — and those hours matter."

References

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